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Thu, 11 Jun 2026 02:09:41 -0700 (PDT) Received: from localhost.localdomain ([2408:80e0:41fc:0:4a46:1ea3:200a:5fb2]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c164f8792bsm279519355ad.23.2026.06.11.02.09.39 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 11 Jun 2026 02:09:41 -0700 (PDT) From: fuqiang wang To: Marc Zyngier , Oliver Upton , Zenghui Yu , linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev Cc: dongxu zhang , wangfuqiang49 Subject: [PATCH 0/2] KVM: arm64: Fix MPIDR lookup for unreset vCPUs Date: Thu, 11 Jun 2026 17:09:32 +0800 Message-ID: <20260611090934.84469-1-fuqiang.wng@gmail.com> X-Mailer: git-send-email 2.47.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: wangfuqiang49 Hi, This series fixes an MPIDR lookup issue when a VM is created with CPU hotplug support. kvm_init_mpidr_data() builds a compressed MPIDR-to-vCPU lookup table by walking all possible vCPUs. However, vCPUs that have not been reset yet still have a zero MPIDR_EL1 state, which aliases vCPU0. This can cause cmpidr_to_idx[0] to be overwritten with the index of an unreset vCPU. As a result, MPIDR 0 lookups can return the wrong vCPU, preventing interrupts targeting vCPU0 from being delivered correctly and making guest boot extremely slow in configurations using CPU hotplug. Patch 1 adds named definitions for the MIDR_EL1 RES1 bit used to detect whether a vCPU's MPIDR_EL1 state has been reset. Patch 2 skips unreset vCPUs when populating the compressed MPIDR lookup table. Thanks, Fuqiang fuqiang wang (2): arm64: Add MIDR_EL1 RES1 definitions KVM: arm64: Skip unreset vCPUs in MPIDR lookup table arch/arm64/include/asm/cputype.h | 2 ++ arch/arm64/include/asm/kvm_emulate.h | 9 +++++++++ arch/arm64/kvm/arm.c | 10 ++++++++++ 3 files changed, 21 insertions(+) -- 2.47.0